Joint Bit Allocation and Hybrid Beamforming Optimization for Energy Efficient Millimeter Wave MIMO Systems

TL;DR

This paper proposes a joint optimization of bit resolution and hybrid beamforming in millimeter wave MIMO systems, leading to improved energy efficiency through a novel matrix factorization approach and dynamic DAC/ADC bit allocation.

Contribution

It introduces a new decomposition of hybrid precoders and combiners and an efficient alternating direction method of multipliers solution for energy-efficient system design.

Findings

Achieves higher energy efficiency compared to fixed-bit methods.

Dynamic DAC/ADC bit allocation improves system performance.

Proposes a novel matrix factorization approach for hybrid beamforming.

Abstract

In this paper, we aim to design highly energy efficient end-to-end communication for millimeter wave multiple-input multiple-output systems. This is done by jointly optimizing the digital-to-analog converter (DAC)/analog-to-digital converter (ADC) bit resolutions and hybrid beamforming matrices. The novel decomposition of the hybrid precoder and the hybrid combiner to three parts is introduced at the transmitter (TX) and the receiver (RX), respectively, representing the analog precoder/combiner matrix, the DAC/ADC bit resolution matrix and the baseband precoder/combiner matrix. The unknown matrices are computed as a solution to the matrix factorization problem where the optimal fully digital precoder or combiner is approximated by the product of these matrices. A novel and efficient solution based on the alternating direction method of multipliers is proposed to solve these problems at both the TX and the RX. The simulation results show that the proposed solution, where the DAC/ADC bit allocation is dynamic during operation, achieves higher energy efficiency when compared with existing benchmark techniques that use fixed DAC/ADC bit resolutions.